The invention relates to an energy drag chain for guiding tubes, cables or the like between two points of connection that can be moved relative to each other, the chain having a plurality of chain members hinged to one another, each having two lateral, flat links and cross-members inter-linking the flat links.
In horizontal use of such an energy drag chain, one chain end is usually attached to a stationary point of connection, and the other chain end is attached to a horizontally mobile point of connection of the energy consumer. Connected to the stationary point of connection is a straight chain section, which is referred to as the lower strand and is laid on a support surface of the stationary base or on the inside of a guide channel. The lower strand transitions via a deflection zone in the chain into a self-supporting upper strand, or one that slides at least partially on the lower strand or on slide rails of the guide channel. The upper strand is attached to the point of connection of the mobile energy consumer.
If the energy drag chain is operated in push mode by the mobile energy consumer, chain members pivot out of the deflection zone or upper strand and into the extended position of the lower strand, their full surface thereby hitting against the support or the guide channel.
In order to dampen the noise generated in the process, noise-damping, cellular rubber strips were provided on the support surface or in the guide channel. It was found, however, that such damping devices suffer from fatigue over time and are subject to severe wear, particularly with energy drag chains operated at high travel speeds, and that rubber pieces come off which can lead to contamination of the support or the guide channel. Another disadvantage is that the cellular rubber strips have to be mounted during installation of the energy drag chain. Improper mounting can easily impair the noise-reducing function of the rubber strips and the travel behavior of the energy drag chain. The rubber strips cannot be delivered in pre-assembled state with a pre-manufactured system.
An energy drag chain of the type described in the opening paragraph is known from European published patent application EP 0 456 537 A. In the chain members disclosed in this document, skids are provided on the inside of the deflection zone. The skids are used exclusively for sliding the upper strand of the energy drag chain on the lower strand, or on a slide rail provided in a guide channel, and thus to reduce the wear of the associated parts of the chain.
Energy drag chains with skids provided on the inside of the deflection zone are also known from German published patent application DE 196 47 322 A and U.S. Pat. No. 5,020,313. In these chains, the skids serve to avoid wear and noise on chain members that rub together.
An object of the present invention is to provide a device to dampen the noise generated by laying the lower strand of an energy drag chain, which device avoids the disadvantages of the prior art, i.e., which particularly does not lead to the deposit of dirt on the support or the guide channel, and which can be reliably installed and supplied in a pre-assembled state with a pre-manufactured system.
A first solution to this object according to the invention involves an embodiment of the energy drag chain of the type described at the outset, in which the chain members are provided, at least in one chain section, with damping devices made of a soft material, wherein the damping devices are provided on the outer side of the chain in the deflection zone and project from the chain members on this side, and wherein the damping devices are designed as mushroom plugs and display a foot that engages a corresponding groove at the respective point on the chain member.
A second solution to this object according to the invention involves an energy drag chain of the type described at the outset, in which the chain members are provided, at least in one chain section, with damping devices made of a soft material, wherein the damping devices are provided on the outer side of the chain in the deflection zone and project from the chain members on this side, and wherein the damping devices are of strip-like design with a mushroom-shaped cross-section at the top and display a foot that engages a corresponding groove at the respective point on the chain member.
The damping devices can be designed such that they do not suffer from fatigue or wear over a relatively long period of time, meaning that no contamination need be expected. They can be securely mounted on the chain members by the manufacturer and delivered together with the pre-manufactured energy drag chain.
The design according to the invention is advantageous for both short and long travel paths of energy drag chains. It can also be used in vertical applications of energy drag chains. If the chain is suspended in a sheet-metal channel that travels horizontally, the chain hits against the sheet-metal walls of the channel due to the inertial forces acting on it, this leading to considerable impact noise. In order to dampen the noise, damping devices are preferably provided on both of the opposite, narrow lateral surfaces of the lateral flat links, or on the outsides of the cross-members of the chain members.
For better fastening of the damping devices, the groove can have an undercut, into which snaps a corresponding projection on the foot of the damping devices.
In order to mold the undercut on an injection-molded lateral flat link, it can be designed as an opening that runs transverse to the groove and opens on a lateral surface to allow insertion of a mold core.
The damping devices are preferably made of a relatively soft plastic material, such as polyurethane. The damping devices can also be made of a foam or rubber material. The damping material can have greater elasticity or lower hardness compared to the material of which the lateral parts are made.
The damping devices are preferably provided on the lateral flat links of the chain members. In horizontally mobile energy drag chains, in particular, the damping devices can be provided on the narrow lateral surfaces of the lateral flat links running in the longitudinal direction of the chain. The outer surfaces of the cross-members can also be provided with damping devices.